What is Gear Pump? Types of Gear Pump

What is Gear Pump? 

A gear pump is a type of positive displacement pump that uses a set of rotating gears to transfer fluids from one place to another. The gears rotate inside a casing or housing, creating a vacuum that draws in the fluid and then forcing it out through the discharge port.

Gear pumps are commonly used in a variety of industries, including oil and gas, chemical processing, and food and beverage.

Types of Gear Pump

There are two main types of gear pumps:

1. External Gear Pump: In an external gear pump, two gears rotate in opposite directions, with the fluid being carried between the teeth of the gears and the casing. This creates a continuous flow of fluid through the pump.
2. Internal Gear Pump: In an internal gear pump, an internal gear with external teeth rotates inside an external gear with internal teeth. As the gears rotate, fluid is carried from the inlet port to the outlet port.

Both types of gear pumps can be designed with a variety of configurations and materials to handle different types of fluids and operating conditions. They can also be used in combination with other pump types, such as centrifugal pumps, to provide additional pumping power and efficiency.

Working principle of External Gear Pump:

Fig. 1: External Gear Pump

External gear pumps operate by the rotation of two gears, an driver gear and an driven gear, within a casing or housing. As the gears rotate, fluid is drawn into the inlet port and trapped in the space between the teeth of the gears and the casing. The fluid is then forced out through the discharge port as the gears continue to rotate.

Fig. 2: External Gear Pump Working

This creates a continuous flow of fluid through the pump. The tight clearance between the gears and casing allows for high volumetric efficiency and low leakage.

Advantages of External Gear Pump:

1. High volumetric efficiency: External gear pumps have high volumetric efficiency, meaning that they can transfer a relatively large amount of fluid per unit of time.
2. Compact size: External gear pumps are compact in size and can be easily integrated into existing systems.
3. Self-priming: External gear pumps are self-priming, which means that they can draw fluid into the pump without the need for external priming.
4. High pressure capability: External gear pumps can operate at high pressures, making them suitable for high-pressure applications.

Disadvantages of External Gear Pump:

1. Limited viscosity range: External gear pumps are not suitable for handling fluids with high viscosities.
2. Sensitive to abrasive particles: External gear pumps can be sensitive to abrasive particles in the fluid, which can cause damage to the gears and casing.
3. Limited temperature range: External gear pumps may not be suitable for handling fluids at very high or very low temperatures.

Applications of External Gear Pump:

1. Lubrication systems: External gear pumps are commonly used in lubrication systems for engines, gearboxes, and other machinery.
2. Hydraulic systems: External gear pumps are often used in hydraulic systems for industrial equipment and machinery.
3. Chemical processing: External gear pumps can be used for transferring chemicals in chemical processing plants.
4. Oil and gas: External gear pumps are commonly used in the oil and gas industry for transferring crude oil, refined products, and other fluids.

Working principle of Internal Gear Pump:

Fig. 3: Internal Gear Pump

Internal gear pumps, also known as gerotor pumps, operate by the rotation of an internal gear and an external gear within a housing. The internal gear has one less tooth than the external gear, creating a series of crescent-shaped chambers between the teeth. As the gears rotate, fluid is drawn into the inlet port and trapped in the crescent-shaped chambers. The fluid is then forced out through the discharge port as the gears continue to rotate. This creates a continuous flow of fluid through the pump.

Advantages of Internal Gear Pump:

1. High efficiency: Internal gear pumps have high volumetric efficiency, meaning that they can transfer a relatively large amount of fluid per unit of time.
2. Wide viscosity range: Internal gear pumps can handle a wide range of viscosities, making them suitable for a variety of applications.
3. Quiet operation: Internal gear pumps operate quietly, making them suitable for applications where noise is a concern.
4. Good suction capability: Internal gear pumps have good suction capability, which means that they can draw fluid into the pump from low pressure sources without the need for external priming.

Disadvantages of Internal Gear Pump:

1. Limited pressure capability: Internal gear pumps may not be suitable for high-pressure applications.
2. Sensitive to abrasive particles: Internal gear pumps can be sensitive to abrasive particles in the fluid, which can cause damage to the gears and housing.
3. Limited temperature range: Internal gear pumps may not be suitable for handling fluids at very high or very low temperatures.

Applications of Internal Gear Pump:

1. Lubrication systems: Internal gear pumps are commonly used in lubrication systems for engines, gearboxes, and other machinery.
2. Hydraulic systems: Internal gear pumps are often used in hydraulic systems for industrial equipment and machinery.
3. Chemical processing: Internal gear pumps can be used for transferring chemicals in chemical processing plants.
4. Food and beverage processing: Internal gear pumps are commonly used in food and beverage processing applications, such as transferring viscous liquids like syrup and chocolate.